1. Technical Field
The present invention relates to a night vision system for detecting objects at relatively low visibility light levels. In particular, the invention concerns an active night vision system having a GPS-based anti-blinding scheme.
2. Background of the Invention
Night vision systems are utilized to allow a user to see objects at relatively low visibility light levels. Night vision systems typically are classified as either passive night vision systems or active night vision systems. In known passive night vision systems used in automotive applications, mid-infrared cameras are used to image objects using the ambient infrared light emitted by the objects in the environment. Mid-infrared night vision systems have relatively few pixels and, accordingly, images formed using such cameras have low video resolution and a relatively narrow field of view. Known active night vision systems utilize a near-infrared (NIR) diode laser or a filtered incandescent light source. The NIR light is subsequently reflected off objects in the environment and is received by a camera. The camera generates a video signal responsive to received light.
An improved active night vision system is disclosed in U.S. Pat. No. 6,429,429 entitled xe2x80x9cA Night Vision System Utilizing A Diode Laser Illumination Module And A Method Related Thereto,xe2x80x9d which is herein incorporated by reference. That application describes an active night vision system that uses a NIR diode laser to illuminate the region forward of the vehicle and a CCD camera to process and display images within the illuminated region. Because NIR light is invisible to the human eye, the laser light can be formed into a high beam pattern to illuminate potential hazards without blinding oncoming vehicle operators. Such systems, however, are susceptible to blinding by oncoming vehicles similarly equipped with a night vision laser illuminator.
Thus, there is a need for a night vision system and method related thereto that mitigates or eliminates blinding of the vehicle night vision system by similarly equipped approaching vehicles.
The present invention provides a night vision system and method related thereto for detecting objects at relatively low visibility light levels and mitigating the blinding effects of nearby similarly equipped vehicles. A night vision system in accordance with one embodiment of the present invention includes an illuminating device such as a NIR light source and beam-forming optics for illuminating a region in the forward direction of travel of the vehicle. A receiver, such as a camera, receives light reflected off objects in the illuminated region and generates a video signal responsive to the received light. A global positioning system (GPS) receiver is also included in operative communication with the GPS network for generating an absolute time value and vehicle directional data. The controller periodically pulses on and off the illuminating device and the receiver as a function of the vehicle directional data and the absolute time signal received from the GPS system. Specifically, the controller generates a vehicle-heading-dependent phase delay from the common timing signal to gate on and off the illuminating device and receiver. The phase delay is scaled so that the illumination devices of oppositely traveling vehicles are pulsed 180xc2x0 out-of-phase with each other. In this way, the system cannot xe2x80x9cseexe2x80x9d the light source of the other, approaching vehicle.
The present invention is advantageous in that it does not require any means for detecting the light source of an opposing vehicle and reacting thereto. Rather, the commonly available GPS time signal is used to provide a vehicle-directional-dependent phase delay for gating the illuminating device and receiver.
Other advantages and features of the invention will become apparent to one skilled in the art from the following detailed description and the accompanied drawings illustrating features of the invention by way of example.